Thus, however far the consequences of Lobachevski's hypotheses are pushed, they will never lead to a contradiction.

Lobachevski has proved not, by creating non-Euclidean geometry.

If Lobachevski's geometry is true, the parallax of a very distant star will be finite; if Riemann's is true, it will be negative.

What victory heralded the great rocket for which young Lobachevski, the widow's son, was cast into prison?